1. Field of the Invention
The present invention relates to an improvement of a knitted-in slide fastener in which a continuous fastener element row of synthetic resin is bound by knitting into a side edge of a fastener tape at the same time when the warp knitted fastener tape is formed by knitting.
2. Description of the Related Art
This kind of the knitted-in slide fastener, which has been practically used, has been disclosed in Japanese Patent Application Laid-Open No. 10-42915 with a production method thereof. The knitted-in slide fastener,as exemplified in the publication, has an attaching portion of a fastener element row along a side edge in the longitudinal direction of the fastener tape. The attaching portion is comprised of chain knitting yarns of four wales, warp in-laid yarns knitted such that they are inverted alternately into chain knitting yarn stitches of the three outermost wales, weft in-laid yarns inserted in a zigzag shape successively over three wales of each wale of all courses and weft in-laid yarns inserted in a zigzag shape over respective two wales of the two wales inside and two wales outside of the tape. This specification describes that when the knitting density of a knitted slide fastener stringer is rough, heat shrinkage fiber such as modified polyester resin may be used as all the weft in-laid yarns.
At the same time when the fastener tape is knitted with the aforementioned knitting structure, synthetic resin monofilament is inserted in the weft-direction into the fastener element attaching portion so that a continuous coil-shaped fastener element row is molded and simultaneously knitted therein to bind and produce a fastener stringer. In the aforementioned fastener stringer, a leg portion of each of the fastener element portions arranged in parallel is tightened and bound by needle loops of the chain knitting yarns from above and all the other structures are disposed on a bottom face of the fastener element row.
Not only in a conventional knitted-in slide fastener of this kind, but also in a slide fastener in which the continuous fastener element row is fixed to the fastener tape by sewing as well as the aforementioned knitted-in slide fastener disclosed in the above publication, the fastener element row is placed and fixed on the surface of the fastener tape. Thus, a height of the surface of the tape is substantially equal to a thickness of the two leg portions stacked vertically.
Recently, a thin clothes material excellent in soft feeling, for example, knitted fabric, has been often used in clothes field. The aforementioned knitted-in slide fastener or a woven-in slide fastener composed of thin and flexible material and structure has been used in these clothes.
As described above, the fastener tape itself should be flexible and the fastener element row to be attached thereto should also be flexible since it is synthetic resin monofilament molded in a coil shape or zigzag shape. However, attachment of the aforementioned flexible fastener element row onto the aforementioned flexible fastener tape is carried out basically in the same way as attachment of the fastener element row to other general fastener tapes. In other words, since in the knitted-in or woven-in slide fastener, the leg portion of each element portion of the fastener element row is tightened and bound with plural binding yarns, a portion to which the fastener element row of the slide fastener is attached is stiffened, so that the slide fastener itself which must be flexible is made into a bar-like condition. Consequently, when such a slide fastener is attached to clothes by sewing or the like, there arises a great feeling of discomfort. This is the same when the fastener element row is fixed to the fastener tape by sewing.
Thus, it can be considered to employ flexible material for the fastener stringer itself, namely the fastener tape itself and the structuring material itself of the fastener element row itself or use fewer binding yarns to attach the fastener element row onto the fastener tape and at the same time, weaken the tightening force. However, in this case, the fastener element row is likely to be deformed or moved easily. As a result, the coupling strength of the fastener elements decreases so that a slip-out of the coupling is likely to occur and therefore, the function as a slide fastener is lost.
Further, when a fastener element row of a conventional slide fastener is attached, as described above, the fastener element row is placed on the surface of the fastener tape and fixed thereto. The height of protrusion above the surface of the tape is substantially the same as a thickness of two leg portions stacked vertically. Thus, when thin clothes employing this slide fastener is ironed, a trace of the fastener element row is clearly left on the fabric.